Apparatus for measuring thixotropy



F.w. c aopwm ET'AL. APPARATUS FOR MEASURING THIXo'raorY Filed Aug, 13, 1940 ll H If Patented Nov. 24,1942

panyingdrawing in which; l V

the apparatus, parts Francis W. Godwin and Martin H. Heeren, Chicago, 111., assignors to Carter Coal Company; a New York, N. Y., a corporation of Delaware Application August 13, 1940, Serial No. 352,469

4 Claims. (Cl. 265-41) This invention relates to force measuring de- I vices and is concerned particularly with an apparatus for measuring the thixotropic properties of liquids such as fuel oils. I The term thixotropy has been-applied 'to a property of certain liquids to-resist small shearing forces, as if a semi-rigid network or gel structure existed in them. Liquidshaving this property of resisting 'smallshearing forces will nevertheless flow' upon the applicationof a slightly greater shearingforce and will in every way act as an ordinaryoliquid should. Upon being allowed to stand quiescent, however; such liquids will again assume I shearing forces.

The amount of shear resistance in thixotropic liquids is exceedingly small, in fact so small as to ordinarily pass unnoticed. Nevertheless: the resistance is often great enough to be of considerable value in-rthat itwill support in suspension small particles such as appear in coal'dust, etc.

-Obviously, the greater the degree of'thixotropy in a liquid the greater the percentage by weightf V .of powdered material which can be s'u's'pe'nded" therein. Hence it is often highly; desirable to determine the degree "of thixotropy 'in various liquids for commercial purposes. V

In view of the foregoing'it is an object of the present invention to provide an instrument for accurately measuring the shearing force *of liquids under uniformconditions.

, Another object of the invention residesin the construction of a thixotrometer which is highly sensitive and consequently'capable of measuring i extremely small forces such as the shearing forces; of liquids having varying degrees ofthe fthixo-1 tropic property. V

.Other objects and advantages t: -;the'*inven- Y tion will be apparent from the following description-when taken in connection witli the accom- Figure 1 is a vertical sectional view through being indicated in'dotted outline.

' Figure 2 is a detail elevational-view of'a :disc

and scale. I f g Figure 3 is a planview of the apparatus, and Figure is a section taken online l-lof Figure 1; V I i I Referring to the drawing in moredetail the numeral 1 indicates generally one embodiment ot a force measur'mg instrumentior measuring small shearing forces in various liquids, but it other formswithout changing the basic principles:

involved. V v.

"Numeral 2 indicates. the-;.upper portion of a cylindrical casing formed ofbrass or the like,

of while numeral ,3 indicates"thelowersection of the casing. 'Thsections 2' and 3; may be de-:

tachablyconnected'by bayonet joints consisting of i'theplates :4 secured .to the upper section} and provided with L-shaped'slotsf5, and screwsifsecured to the lo wer section '3; for cooperation with the slots. It will be apparent thatby loosentheir resistance to small ing'the 'screwsffi and slightly rotatingthe lower 7 section, the same may-be readily detached from 'the upper section. reversal of. the'operations tom: of section 3 isa sample cup I. This cup is open at its. upper end and is in communication withthe casing or jacket 2 -3. The upper end of thejcup preferably extends slightly above the bottom of section 3 of the casing so as to provide iannular overflow chamber around theQpup.

7 On" the exterio'rpf'thebottom of the 0115 1 is. a

-' "bearing member 8 adapted to rest'upon' a pivot point 9 of aisuppo'rting frame Ill. The legs H or the framel0 are providedwith screwsfll l which lightly contact the "jacket'oi casing 2- -3 i and thus serve'as a means for leveling the ap ooperation'j with a pivoted level Lil paratus in mounted' ona head it of the casing. 7

"-Rotatably mounted inthehe'ad ll is a vertical I shaft'lij from which is suspe'ndeda torsion wire a ll. Set screws i8 and serve to ,detachably' ended cylindrical'rotor20,"preferably of aluminum; and ofslightly; less diameter thanthe 5 'A' water batli, i5 may be empl'oyed toimain- V tain "a uniform temperature in the sample cup I and preferably. should extendfslightly above-the bottom-of the casing 3.

connect wire, IT to the torsion head it, andsecured to the'lower end of the'wireisan opensample cup 1.; Any suitable: meansmay beam-- will be understood that the instrument may take ployed for attaching the torsion wire,,.to the cylinder 20, and in the embodiment of the invention'shown herein the means comprises a pair "of clamping plates 2|. These. platesaresecuredf *at their ends to the upper end of C li der 20 and grip.,the lower en'd'ofwirel'l at their center. 1

Also'mountedon the-clamp 2| is a rod which serves as'a supportfor a mirror 23 as will appear hereinafter. Fixed to'the'upper end or the torsion head or. shaft 16 is a horizontally extending arm fl' havin: an arcuate end 25 cut into the iorzii of a will, of course, provide a ,rigidconnection be.- "tween the upper andlower sections of .the casingl Fixed to or integrally connected with the'botv second standard 30 secured to the upper surface of head ll forms a support for a worm clock motor 3|. The shaft of the motor 3! and the shaft 21 may be releasably coupled by a sleeve 32 and set screws 33.

Amxed to the outer end of the worm shaft 21 is a calibrated disc 34 for cooperation with a pointer 35 mounted on the head H. A knob 36 is secured on the outer end-of shaft 21 for manual operation thereof under certain conditions. I

As will be noted from an inspection of Figure l, the lower section 3 of the casing is provided with an arcuate slot 31 at the height of the mirror 23 which is supported on the rotor 20. 'An ordinary lamp and scale assembly represented generally at 38, is mounted for cooperation with the slot 31 and mirror 23.

In the operation of the measuring instrument, the sections 3 and sample cup 1 are removed from the main body of the casing, and asample of the oil or other liquid to be tested isplaced in the cup. This part of the apparatus is then reattached to the main casing 2 and placed in the supporting frame ill with the bearing 3 supported on the pivot point 9. The screws I2 are then manipulated in conjunction with the level l3 so as to bring the instrument into exact vertical position with the rotor 20 concentrically arranged in the cup 1. The bath I 5 may be placed in operation if desired.

Before starting the motor 3|, the set screws 33 are loosened in sleeve 32 so as to disconnect the motor shaft from the worm shaft 21. Knob 36 is then operated to rotate the torsion head It and wire l1 to bring the mirror 23 into the desired starting position. It may be desirable to as a measure of the thixotropic property of the particular liquid.

In some liquids the thixotropic property is re- I stored after disturbance more rapidly than in other liquids, and this quality of a liquid may be measured by intermittent use of the present measuring instrument.

' From the foregoing description and the accompanying drawing it will be apparent to those by one having little if any skill in the particular art.

In accordance with the patent statutes we have described what we now believe to be the preferred form of construction of the force measuring ap-' paratus, but it is obvious that many minor changes containing a liquid to be tested, an open-ended cylindrical rotof'ffonyse with the cup, a torsion wire for suspending the rotorin a liquid in the cup, means for applying a torsional force directmake this adjustment prior to placing the charged sample cup in position. However, if the adjustment is made after the sample to be tested is in final position, then some little time must be allowed to elapse before the actual measuring operation is begun so as to allow the liquid sample to return to a quiescent state. I

Assuming that the parts are in the position shown in Figure 1, with the mirror properly position'ed. with respect to the lamp and scale 33, -motor 3| coupled to shaft 21, and the cup 1 charged with a sampleliquid to be tested, the

position of the scale on disc 34 is read with respect to the pointer 35, and the motor is then started. The liquid in the cup'1, if it'has any 'thixotropic property will hold the rotor 20 against movement until such time as the torsional force stored in the .wire l1 overcomes the shearing force of theparticular liquid being tested. Initial movement of the rotor 20 is indicated by amove-' ment of the pencil of light on the scale 38 and at that instant the motor 3| is stopped and the number 01 rotations and fraction thereof of shaft [21 is indicated. The amount of force required as disturb the oil is a direct function of the 1y to the wire,, and means associated with the rotor for indicating initial movement thereof.

2. A thixotrometer comprising a' sample cup for containinga liqiilmtg be tested, a rotor for use with the cup, marathwir for suspending the rotor in a liquid in the cup. a casing for said parts, means for applying a torsional force directly to the wire, said casing being provided with an opening, a reflector rigidly connectedto the rotor and in substantial alignment with'the opening, and means for projecting a light beam through the opening onto the reflector toindicate the initiation of relative movement between the rotor and cup.

3. A thixotrometer comprising a sample cup for containing a liquid to be tested, a rotor for usewith the cup, a torsion wire for suspending the rotor in a liquid in the cup, a motor, gearthe gearing for manually operating the same when th coupling is released, and means associated r with the rotor for indicating the initiation of relative movement between the rotor andcup.

amount oi rotation of the head l5 necessary to;

, elect movement of the rotor 23, and hence the extent of rotation of the head may be considered 4. In a thixotrometer a casing, a sample cup disposed at the bottom of the casing for containing a liquid. to be tested, a rotor for use with the cup, a torsion wirefor suspending the rotor in a liquid in the cup, means for applying a torsion-a1 force directly to the wire, a level on said casing, a pivot point on which said casing is mounted, and means cooperating with a wall of the casing for adjusting the same to an exact vertical position.

FRANCIS W. GODWIN. MARTIN H. HEEREN. 

